Re: [PATCH v3 08/13] tty: serial: qcom-geni-serial: refactor qcom_geni_serial_handle_tx()

Jiri Slaby
2022-11-24T07:18:23Z

On 23. 11. 22, 12:07, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
>
> qcom_geni_serial_handle_tx() is pretty big, let's move the code that
> handles the actual writing of data to a separate function which makes
> sense in preparation for introducing a dma variant of handle_tx().
>
> Let's also shuffle the code a bit, drop unneeded variables and use
> uart_xmit_advance() instead of handling tail->xmit manually.
>
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> ---
> drivers/tty/serial/qcom_geni_serial.c | 54 +++++++++++++--------------
> 1 file changed, 27 insertions(+), 27 deletions(-)
>
> diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
> index 68a1402fbe58..658b6d596f58 100644
> --- a/drivers/tty/serial/qcom_geni_serial.c
> +++ b/drivers/tty/serial/qcom_geni_serial.c
> @@ -704,19 +704,42 @@ static void qcom_geni_serial_start_rx(struct uart_port *uport)
> writel(irq_en, uport->membase + SE_GENI_M_IRQ_EN);
> }

I know you just shuffle the code, but:

> +static void qcom_geni_serial_send_chunk_fifo(struct uart_port *uport,
> + unsigned int chunk)
> +{
> + struct qcom_geni_serial_port *port = to_dev_port(uport);
> + struct circ_buf *xmit = &uport->state->xmit;
> + u8 buf[BYTES_PER_FIFO_WORD];
> + size_t remaining = chunk;

Why size_t when the others are uints? Well, BYTES_PER_FIFO_WORD should
be defined as 4U.

> + unsigned int tx_bytes;
> + int c;
> +
> + while (remaining) {
> + memset(buf, 0, sizeof(buf));
> + tx_bytes = min_t(size_t, remaining, BYTES_PER_FIFO_WORD);

Then, no need for min_t.

> +
> + for (c = 0; c < tx_bytes ; c++) {
> + buf[c] = xmit->buf[xmit->tail];
> + uart_xmit_advance(uport, 1);
> + }
> +
> + iowrite32_rep(uport->membase + SE_GENI_TX_FIFOn, buf, 1);

I wonder, why is _rep variant used to transfer a single word? Only to
hide the cast?

thanks,
--
js
suse labs